A dielectric porcelain composition tends to exhibit a greater dielectric loss as the frequency used increases. Therefore, a dielectric porcelain composition having a great dielectric constant (hereinafter referred to as ".di-elect cons..sub.r ") and a great unloaded Q value (hereinafter referred to as "Q.sub.u ") in microwave range has been desired. Further, a dielectric porcelain composition having a small resonance frequency temperature coefficient (hereinafter referred to as ".tau..sub.f ") as well as good .di-elect cons..sub.r, Q.sub.u and .tau..sub.f values has been required.
As such a dielectric porcelain composition there is disclosed a composition comprising MgO, TiO.sub.2 and SnO.sub.2 in JP-A-8-231269 (The term "JP-A" as used herein means an "unexamined published Japanese patent application"). The proposed dielectric porcelain composition comprises a small amount of SnO.sub.2 incorporated therein and allegedly exhibits a high Q value as compared with the conventional materials. However, no reference is made to .tau..sub.f. Further, JP-A-7-201223 discloses a dielectric porcelain composition comprising TiO.sub.2 and a relatively large amount of SnO.sub.2. This composition exhibits excellent .di-elect cons..sub.r and Q.sub.u values. However, the dielectric porcelain composition comprising two components can difficultly have its dielectric properties adjusted as desired by changing the formulation. In particular, no products having an excellent .tau..sub.f value, i.e., around 0 ppm/.degree.C. can be obtained unless the composition has a high SnO.sub.2 proportion.